Recommendations for new filter holder

I have been using the Cokin P series filter holder for my Mamiya 645, but I am thinking of changing holder and filters for something a little les fiddley than the plastic P holder. I have the holder that stacks 3 filters which is nice but if I use it on my 45mm wide angle lens it creates a vignette. I am wondering if someone can recommend another type of filter system that is easy to operate in the field and sturdy. This would be for tripod work shooting landscape/city stuff. Cost is a consideration, although I don't have a problem paying for something that is worth it, but if you know a system that gets me 90% better quality for 50% cost increase then that would be something to think about. Any thoughts are encouraged.

Thanks,
D.